Mechanical loaders



y 1, 1963 K. E. DENHAM 3,090,511

MECHANICAL LOADERS Filed Aug. 1. 1960 3 Sheets-Sheet 1 I G 1 N KENNETH E. DEA/MM WM, M

INVEA/T'OR May 21, 1963 K. E. DENHAM MECHANICAL LOADERS 3 Sheets-Sheet 2 Filed Aug. 1, 1960 INVENTOR lf- NNET/v E. DEN/MM May 21 1963 K. E. DENHAM MECHANICAL' LOADERS Filed Aug. 1, 1960 3 Sheets-Sheet 3 K ENNETl-f E. DENH-AM This invention relates to improvements in or relating to mechanical loaders and is particularly concerned with improvements in mechanical overshot loaders for use in the sinking of mine shafts or the like.

Mechanical overshot loaders have been used for some time in connection with the sinking of mine passages which have an inclination to the horizontal of not more than about 30. Shafts which have an inclination to the horizontal of more than about 50 are usually sunk by clam-shell buckets suspended from wire ropes. It has not hitherto been convenient to sink passages which have an inclination of between 30 and 50 since neither the standard overshot loader nor the clam-shell bucket will operate efficiently at these angles. In this specification the term mine passage is used to denote any passage, shaft, winze or tunnel in a miner, and may even be used to cover an inclined ramp or embankment.

It is an object of this invention to provide a simply improved or modified overshot loader which will operate satisfactorily at inclinations between 30 and 50.

Accordingly, we provide an improved mechanical overshot loader, particularly for use in the sinking of mine passages having an inclination to the horizontal of approximately 30 to 56, said loader having; a wheeled body, a pair of bucket arms situated one on either side of the body, a bucket mounted on the forward ends of said bucket arms, the rear end portion of each bucket arm shaped so as to provide a curved rolling surface, at least one lifting chain or the like having one end secured to the front portion of the lifting arms and the other end secured to a take up drum which is driven by a suitable motor and is positioned to the rear of the body so that its axis lies substantially transverse thereto; and characterised in that two parallel longitudinally extending guide-ways are provided, one on either side of the body, so that the curved surfaces of the bucket arms may roll thereon when the chain is reeved onto the drum and the bucket is drawn rearwardly over the body of the loader, the guide-ways terminating before the rear end of the normal rolling path so as to form a point or apex about which the bucket arms can pivot for the res-t of the bucket travel so that the movement of the bucket is facilitated.

More particularly, the invention may also include travel modifications comprising rope drums associated with the wheels thereof and an additional sheave wheel attached to the body of the loader, the said rope drums and sheave wheel being adapted to take the ropes by which the loader is moved.

The invention may also include a mechanical overshot loader having either one of the above modifications and including balance modifications comprising an additional wheel or pair of wheels situated forward of the loader body and attached thereto so as to help to prevent the forward tipping of the loader.

The invention may also include a loader having a tipping modification comprising a bucket attached to the bucket arms by a transverse pivot or pivot pins arranged so that the bucket swings into its loading position when the arms are down in front of the loader and so that the bucket swings into a dumping position when the arms are up at the back of the loader.

Finally the invention may include an overshot loader 3,093,511 Patented May 21, 1963 which includes a locking modification wherein locking means are provided for fixing the pivoted bucket in the dumping position even when the bucket is in the loading position.

In order to further elucidate the nature of the invention a particular example of an overshot loader formed in accordance with the invention will now be described with reference to the accompanying drawings by way of illustration only. In the accompanying drawings:

FIGURE 1 is a side elevational view of a loader formed in accordance with this invention shown horizontal and in the digging position;

FIGURE la is a detail of the rear wheel arrangement of FIGURE 1;

FIGURE 2 is a side elevational view of a loader typical of those previously known in the art shown on an incline within the range herein considered;

FIGURE 3 is a view similar to that of FIGURE 2 but illustrates the loader of FIGURE 1 in the discharge position;

FIGURE 4 is a plan view of the loader of FIGURE 1 which includes a rope and pulley arrangement;

FIGURE 5 is a view of a loader very similar to that of FIGURE 4 except that a modified rope and pulley arrangement is used;

FIGURE 6 illustrates an elevational view of a loader very similar to that of FIGURE 3 excepting that the bucket is shown in the forward locked position and FIGURE 7 is a detail of the bucket assembly of FIG- URE 6.

Although the mechanical loader of this invention is illustrated in considerable detail in FIGURE 1 of the accompanying drawings, the loader shown in FIGURE 2 will be referred to first since it illustrates the form of loader typical of the prior art.

Certain known mechanical overshot bucket loaders (see FIGURE 2 include a wheeled body 1, a pair of bucket arms 2 having a bucket 3 or the like attached to their forward ends and having their rear ends shaped so as to provide curved rolling surfaces 4. The body 1 houses (often as an integral fitting) a pneumatic or an electric motor (not shown) which, through suitable gearing, effects the reeving of a chain 5 around a single lap drum or shaft 6, one end of the chain 5 being attached to the drum 6 and the other to the bucket arms 2. A pair of normally horizontal parallel rail-like guide-ways 7 are provided one on either side of the body 1 and are adapted to support the curved surfaces 4 of the bucket arms 2 i so that the bucket arms are free to roll thereon. The arms 2 are arranged on the guide-ways 7 so that, as the chain 5 is wound upon the drum 6 the arms 2 rotate, rolling on their rear surfaces 4 rearwardly along the guideways 7, so that the bucket 3 passes from the front, over the top, to the rear of the loader. Bumper springs 8 are provided at the end of the path of the bucket arms 2 so that the arms knock into them thereby helping in the ejection of the material carried in the bucket 3 In order to eifectively eject the material from the bucket 3, the bucket 3 and its contents are accelerated during their travel from the front to the back of the loader so that the velocity of the bucket 3, when the arms 2 strike the bumpers 8, is comparatively large. The discharge of maten'al is normally effected without undue power consumption by taking advantage of the balance of the bucket 3, arms 2 and the load near the discharge point. During the digging operation the bucket 3 is situated near or on the ground (as in FIGURE 2) at the front of the loader and the chain 5 is out-reaching to the bucket arms 2 and the effective radius of the drum 16 is small while the bucket lever arm is large. As the full bucket 2 is raised the chain 5 is Wrapped around the rotating drum 6 thereby increasing the eifective'radius of the drum and decreasing the effective lever arm acting on the bucket 2. Thus, for a given drum speed, the speed of the bucket and bucket arms is proportional to the amount of chain wound upon the drum, but the actual relationship is also dependent upon the contour of the curved bucket arm surfaces.

The distance between the point of attachment of the chain to a bucket arm 2 and the point of contact between the curved surface 4 of the bucket arm 2 and one of the guide-ways 7 is the effective lever arm by which the bucket 2 is raised. The rolling surfaces 4 of the bucket arms 2 are shaped in such a manner that the etfective lever arm is longest when the bucket 2 is in its loading position (FIGURE 2 full lines) and is practically zero when the bucket is in its discharge position (FIGURE 2 dotted lines). This feature also effects the acceleration of the bucket 2 during its travel from the loading position to the discharge position.

However, a standard overshot loader such as that outlined above Would only operate effectively in the horizontal or near horizontal inclination. As the loader is inclined more and more to a horizontal, the resistance to the rotation of the bucket at discharge increases since it is no longer balanced and the motor must pull the bucket arms and bucket against the force of gravity during the entire motion of the bucket, even just prior to discharge (viz; FIGURE 2). It has been found that at inclinations to a horizontal of over 30 the pneumatic or electric motor cannot throw the bucket and the bucket arms as required and often stalls before the bucket reaches the discharge position and before the bucket arms reach the bumpers. If the motor does not stall, the discharge may still be very inefficient at these inclinations.

In addition to this disadvantage various other disadvantages become apparent as soon as the standard loader is forced to operate on steep inclines. For example, the traction motor is no longer able to move the loader up the incline (both because of inadequate power and because of wheel slip), the loader tends to tip forward when digging, the material which is discharged from the bucket 2 often does not clear the rear of the loader and :fails to fall in the loading box 9 or even leave the bucket 2, and finally, the bucket 2 still faces upwards at the discharge position (viz; FIGURE 2) making discharge and ejection of the material difiicult.

The overshot loader of this particular embodiment of the invention is illustrated in FIGURE 1 and is an overshot loader substantially as described with reference to FIGURE 2, but it includes various modifications and improvements which adapt it for operation at angles between 30 and 50 of inclination to the horizontal. The improvements and modifications allow the overshot loader of the invention to operate effectively at these angles without it being necessary to enlarge or replace the driving motor or to build up an especially designed loader.

The first modification which is made to the mechanical loader of the above description may be called the throwing modification and is made in order to compensate for the effect of gravity on the bucket and =load when the loader is inclined to the horizontal. The two parallel longitudinally extending guide-ways 7 which are provided one on each side of the body of the loader so as to take the rolling surfaces 4 of the bucket arms 2 are each made to support a fiat wedge 71:. Alternatively, the guide-ways themselves may be removed from the loader and replaced by wedge-like guide-ways which have the shape of the combined ways 7 and 7a sloping upwardly from the front of the loader towards the rear. The wedge-guides 7a serve to provide paths for the rolling surfaces 4 or the bucket arms 2 in the same manner as the standard guide-ways 7, but terminate at an apex 10 near the rear ends of ways 7 so that each bucket arm 2,'after rollinga certaindistance' up the flatwedgeguides 7a, will pivot on the apexes 10 for the remainder of the buckets motion.

The position of the apex 10 depends upon the slope at which the loader is intended to operate, but is also always such that the rolling surface 4 of the bucket arms 2 pivot thereon before the stalling point of the motor. This modification ensures that the effective lever arm will not substantially decrease after the apex 10 of the flat wedgeguide 7a has been reached. Therefore by suitable arrangement of the fiat wedge-guides 7a, a satisfactory lever arm is provided at all times so that the motor can pull the bucket and bucket arms to the discharge position without stalling.

Another modification is also made to the standard overshot loader and has been termed the travel modification. The standard loader normally travels on near horizontal rails 11 (mounted on sleepers 12) by driving its wheels 13 by means of a pneumatic travel motor operated via a gear train.

Overshot loaders for use on rails 11 having a substantial inclination to the horizontal may include the travel modification to enable the loader to be moved up the incline without having to modify or replace the traction motor and so as to prevent dangerous slipping. Normally, at least the rear wheels are fixed to their axle. However, according to this modification the front wheels 1311 rotate independently of the drive motor and the rear wheels 1312 are mounted so as to rotate freely on the rear axle 14 (see FIGURE la). However, a rope drum '15 is secured firmly to each end of the axle 14 and rotates therewith so as to wind a rope 16 on or off said drum. The modification includes the addition of a sheave block 17 attached to the bottom of the body 1 of the loader between the rear wheels, two pulley blocks 18 being fastened to the rails 11 up the slope behind the loader, and the rope 16 being passed about the drums 15, sheave 17 and blocks 18, as in FIGURE 5. Thus the rope 16 is attached to one drum 15, passed through a pulley block 18 attached to one of the rails 11, passed around the sheave Wheel 17 on the loader, through the other pulley block 18, and the other end is attached to the second drum 15. In this manner a mechanical advantage is obtained by virtue of the sheave wheel, and the traction motor is enabled to pull the loader slowly up an incline of about 50", by winding the rope 16 onto the drums 15.

Where inclines of considerably less than 50 are used a quicker motion of the loader may be obtained by eliminating the sheave 17 and only using the pulleys 18a, as illustrated in FIGURE 4. In such a case smaller wheel drums 15 may be used since less rope is reeved for a given distance of travel as the power required is correspondingly less.

Another modification is the balance modification which compensates for the fact that at an inclination of about 45 to the horizontal the centre of gravity of the loader may lie almost over the front wheels (e. g. FIGURE 2) and there is therefore a tendency for the loader to tip forward making digging impossible. This modification includes an additional bogie comprising the frame 19 and the pair of Wheels 20 situated between the normal front wheels 13a of the loader and the bucket 3. The bogie is firmly secured to the body 1 of the loader as in FIGURE 1. A loader which has this modification becomes more stable and digging is possible.

It may be desirable, however, in certain loaders to lengthen the bucket arm 2 (by the insertion of the extension piece 2a) in order to flit the Wheels 20 between the bucket and the normal front wheels 13a as indicated in FIGURE 1.

A further modification to the loader may also be made which has been termed the tipping" modification since it allows the successful filling of a loading box 9 behind the overshot loader when the latter is operating on a steep slope. Often the bucket 3 of the standard loader operating at the slopes considered willnot clear the 'rear Of the loader when it is in its discharge position. In addition to this disadvantage the normal bucket 3 when operating at a substantial incline still faces upwards at the discharge position making discharge and ejection of the material difiicult (FIGURE 2). The first disadvantage may be overcome by means of the extensions 2a of the bucket arms 2 as described in the balance modification so that bucket 3, when in the discharge position, is therefore made to overhang the loading box.

The second disadvantage may be overcome by modifying the bucket as in FIGURE 1 by pivoting the bucket 3 at or near its rear top by means of the shaft 2 1 and lug 22 and providing stop plates 23 at the back of the bucket which hold it at the required angle for digging. At the discharge position the shaft 21 is below the bucket 3 and the bucket 3 falls downwards under gravity about shaft 21 so as to dump the rocks or soil from the bucket (see FIGURE 3). It has been found advantageous to further modify the tipping of the standard overshot loader by removing the standard bumpers and replacing them with rubber stops 24 or the like which serve the same purpose but take up less room thereby allowing the bucket arms 2 to move further to the rear than normal.

One important advantage of the pivoted bucket modification is that, a locking pin 25 and co-operating lug 26 are provided so that the bucket 3 may be locked in its tipped position with respect to the bucket arms 2. Such a position is useful because of the fact that miners quite often have to pick up the last few rocks etc. by hand and shovel them into the bucket 3, previously the bucket was angled incorrectly for such an operation.

I claim:

1. An improved mechanical overshot loader, particularly for use in the sinking of mine passages having an inclination to the horizontal from about 30 to about 50, said loader comprising a Wheeled body, a pair of bucket arms, one positioned on each side of said body, a bucket mounted on the forward ends of said bucket arms, the rear end portion of each bucket arm being curved for providing a curved rolling surface, at least one lifting chain hav ing one end secured to the front portion of said lifting arms, a take-up drum on the rear of said body to which the other end of said lifting chain is attached, and two parallel longitudinally extending guideways, one along each side of said body and on which the curved rear end portions of said bucket arms roll, said guideways having a profile with an apex therein near the rear end of the guideways at a point just before the end of the normal rolling path of said bucket arms, whereby when the bucket arms are rolling on said guideways they pivot around said apexes and the movement of the bucket for emptying it is facilitated.

2. A loader as claimed in claim 1 in which the plane containing the portions of the guideways to the rear of the apexes is inclined rearwardly from a vertical plane through the body when the longitudinal axis of said body is at an angle no greater than to the horizontal.

'3. A loader as claimed in claim 1 in which said wheeled body comprises two transverse axles each having wheels freely rotatably mounted on the ends thereof, a travel motor associated with the rear axle, and a rope drum fixed on each end of said rear axle, whereby the ends of a rope or ropes can be wound on said drums or let off said drums by operation of the travel motor to draw the loader rearwardly up an incline or allow it to descend along an incline.

4. A loader as claimed in claim 3 in which said wheeled body further comprises a pulley block on the rear of said loader, and a rope having each end attached to one of said drums and having the middle passing through said pulley block.

5. A loader as claimed in claim 1 in which said wheeled body comprises two pairs of wheels on said body, a bogie fixed to the front end of said body, and an additional pair of wheels on said bogie, said bucket arms being sufiiciently long to hold the bucket in front of said bogie and additional wheels, whereby the base of the loader is lengthened to increase the stability thereof on steep inclines.

6. A loader as claimed in claim 1 in which said bucket is pivotally mounted on said bucket arms, said pivotal mounting being above the back of the bucket when the bucket arms are in the forwardly extending position, and the axis of the pivotal mounting extending transversely of said loader, whereby the bucket will pivot back against the bucket arms when it is in the forward loading position and will be swung over the pivotal mounting when the bucket arms are in the rearmost position.

7. A loader as claimed in claim 6 in which said bucket arms have an extension thereon extending below the pivotal mounting of said bucket on said bucket arms, said extension having a low stop thereon against which the bucket abuts when in the forward loading position, a high stop on said bucket arms above the pivotal mounting of said bucket against which said bucket abuts when it is thrown over the pivotal mounting in the discharge po :sition, and a locking means associated with said high stop for locking said bucket in the discharge position when the bucket arms are in the forward loading posit-ion.

References Cited in the file of this patent UNITED STATES PATENTS 2,398,859 Ruddock Apr. 23, 1946 2,495,138 Royle Jan. 17, 1950 2,619,243 Biedess Nov. 25, 1952 2,668,630 Ertl Feb. 9, 1954 2,729,348 Hackett et al. Ian. 3, 1956 2,792,140 Schwartz May 14, 1957 

1. AN IMPROVED MECHANICAL OVERSHOT LOADER, PARTICULARLY FOR USE IN THE SINKING OF MINE PASSAGES HAVING AN INCLINATION TOI THE HORIZONTAL FROM ABOUT 30* TO ABOUT 50*, SAID LOADER COMPRISING A WHEELED BODY, A PAIR OF BUCKET ARMS, ONE POSITIONED ON EACH SIDE OF SAID BODY, A BUCKET MOUNTED ON THE FORWARD ENDS OF SAID BUCKET ARMS, THE REAR END PORTION OF EACH BUCKET ARM BEING CURVED FOR PROVIDING A CURVED ROLLING SURFACE, AT LEAST ONE LIFTING CHAIN HAVING ONE END SECURED TO THE FRONT PORTION OF SAID LIFTING ARMS, A TAKE-UP DRUM ON THE REAR OF SAID BODY TO WHICH THE OTHER END OF SAID LIFTING CHAIN IS ATTACHED, AND TWO PARALLEL LONGITUDINALLY EXTENDING GUIDEWAYS, ONE ALONG EACH SIDE OF SAID BODY AND ON WHICH THE CURVED REAR END PORTIONS OF SAID BUCKET ARMS ROLL, SAID GUIDEWAYS HAVING A PROFILE WITH AN APEX THEREIN NEAR HE REAR END OF THE GUIDEWAYS AT A POINT JUST BEFORE THE END OF THE NORMAL ROLLING PATH OF SAID BUCKET ARMS, WHEREBY WHEN THE BUCKET ARMS ARE ROLLING ON SAID GUIDEWAYS THEY PIVOT AROUND SAID APEXES AND THE MOVEMENT OF THE BUCKET FOR EMPTYING IT IS FACILITATED. 